The karst depression belongs to the accumulative area of surface water and subdrainage area of subsurface water, the karstification is relatively week, and reservoirs are undeveloped.

岩溶斜坡和岩溶洼地为地表水汇集区及地下水排泄区，岩溶作用，发育。

This method can acurately simulate the flow direction in gird near river, and can keep the direction of waterflow from crossing the watershed of subdrainage area.

这样既可以精确地反映出河道附近格网的水流方向，又可以让各个子流域内的汇流方向和水流方向会跨越子流域的分水岭。